To create a favorable environment, the optimum temperature and humidity in all residential and industrial premises use ventilation systems. Depending on the method of air circulation, purpose, design, design and scope of the ventilation system is divided into types. To be sure of the appropriateness of the use of a particular system for a particular room, it is necessary to become familiar with the main types, functions and purpose of ventilation systems.
Classification of ventilation systems
The following types of ventilation systems are distinguished:
Depending on the method of moving air flow:
- with natural impulse (natural ventilation);
- with mechanical impulse (forced ventilation).
Depending on the destination:
- forced ventilation;
- exhaust ventilation;
- combined ventilation.
Depending on the serving area of the room:
- local ventilation system;
- general ventilation system;
- emergency ventilation;
- anti-smoke ventilation.
Depending on the design:
The natural ventilation system is air, not equipped with electrical equipment. Circulation of air in such a system is carried out due to the difference in pressure and temperature of the outside air and the air inside the room, as well as wind pressure. For multi-storey construction, vertical ventilation ducts are arranged, which in the exit area in the premises (kitchen, bathroom) are covered with ventilation grilles. The ventilation channels are taken out of the roof and installed on them deflectors (aerodynamic devices), contributing to the strengthening of the air output through the force of the wind. The flow of fresh air ensures the leakiness of doors and windows, as well as their open position. The movement of air flow in the scheme of the ventilation system of a natural type occurs from the bottom up.
The natural ventilation system of the room, on the one hand, is reliable and durable, as it has no mechanisms and automation, on the other hand, the system is highly dependent on natural factors (air temperature, external air velocity), there is a risk of airway clogging. In addition, with the widespread use in the premises of hermetic plastic windows, the volume of inflow flow has decreased.
In the case when natural ventilation is not able to provide the required air exchange, ventilation systems with mechanical impulses are used. Due to the use of various devices such as a fan, a heat exchanger, a filter, etc. in the circuits, the flow of air takes place regardless of weather conditions. In addition, the forced system is able to clean, heat or cool the supplied air, to regulate the flow rate. Artificial air exchange systems are quite effective, but more expensive to operate and depend on the power supply. Forced installations are equipped with automatic control.
In the scheme of the combined system can be provided exhaust fans, built into the air ducts of the kitchen and / or bathroom. Moreover, the fans can be endowed with artificial intelligence (timer, hydrostat, motion sensor), which will also help avoid unnecessary power consumption. At a time when the device is automatically turned off, the air flow is carried out naturally. Occasionally, window or wall inlet valves are used to increase air flow.
Helpful advice! Combined systems can reduce energy costs and provide the necessary level of air exchange..
Competent calculation of the effectiveness of a ventilation system is made by a specialist.
The intake ventilation system provides an inflow of outside air into the room. With the help of various devices, the incoming air is cleaned, moistened, heated or cooled. Exhaust air is exhausted using exhaust ventilation systems. The operation of the intake and exhaust installation should be based on the calculation of the balanced air exchange.
Air ducts for ventilation. Installation, operation and maintenance of systems. Materials for the manufacture. Ways of connecting elements of the system. Cleaning and disinfecting duct systems.
There is the use of ventilation only supply type, or, conversely, only exhaust. Depending on the ventilation zone in the room, the intake and exhaust ventilation can be local (concentrated in a specific place) or general exchange (serve the entire room).
The ventilation system serving a specific area in the room is local ventilation. Local ventilation provides fresh air a certain place in the room, for example – a working area, while local exhaust ventilation works to remove polluted air in the places of its concentration. The use of local ventilation systems is mainly industrial, as a variant of domestic use of local exhaust ventilation – an extract over the kitchen stove.
The general ventilation system provides ventilation of the entire room. As well as local, general exchange ventilation system can be in two versions – supply and exhaust. The inlet general exchange system is carried out mechanically, since there is almost always a need for purification and heating of the intake air. And general exhaust ventilation can be with a natural impulse (unless otherwise required by the norm) or equipped with simple devices for the withdrawal of polluted air.
A composable ventilation system is individual elements and devices for ventilation, assembled according to a scheme into one system. The advantage of such a ventilation system is that it can be assembled with blocks and devices of individual choice and for different purpose and floor space. It is imperative that the design and calculation of ventilation systems in the type-setting version should be performed by a professional.
In the case of a monoblock ventilation system, all devices and elements of the process are concentrated in a single package (monoblock), equipped with sound insulation. A set of devices in a monoblock installation may be different, but often a heat recuperator enters there. Among the advantages are the ease and speed of installation of the ventilation system, minimum consumables, low noise level. All devices are assembled and tested at the stage of their production, therefore monoblock systems are quite effective.
Air heating is one of the most promising modern types of space heating. The scheme of such a heating system has several advantages:
- combining the functions of heating and ventilation;
- safe operation;
- high sanitary and hygienic indicators;
- use in work of different heat carriers.
Air heating systems perform at the same time work on heating and ventilation. During the heating supply period, they operate using air recirculation. Considering the available sources of heat, the installation of air heating can be equipped with an electric or water heater. Air heating works thanks to the intake ventilation system with a heater heating from the central heating system. The presence of automatic control allows you to select the desired mode of operation and adjust the temperature of the heated room. Air heating systems combined with ventilation are fully capable of providing heat to the entire serviced room.
The result of the calculation of ventilation should be a reliable and easy-to-manage ventilation system that provides the required air exchange with a low noise level. Many in the calculation use prepared calculators for automatic selection of parameters of the ventilation system.
Helpful advice! When calculating the ventilation, mandatory management of state standards and rules expressed in SNiP 41-01-2003, as well as relevant sanitary and hygienic requirements, is required.
The calculation of the ventilation system combines several stages. Air exchange is calculated (air capacity), determined in cubic meters per unit time (hour). For the calculation, an outline of the entire object is made, indicating the size and purpose of each room. Air exchange is calculated by two indicators: the number of people and the multiplicity.
- Calculation of performance by the number of people:
L (required air exchange) = Lnorm x N, where
Lnorm – standard consumption for 1 person;
N is the number of people.
- Calculation by multiplicity:
L (required air exchange) = n x H x S, where
n is the multiplicity (normative) air exchange;
H – height of the room, m;
S – area of the room, m ?.
The value of n for residential properties 1-2, for office 2-3.
From the obtained values of air exchange for ventilation, more is taken.
The calculation of the air ducts is made after the scheme of the air duct network has been drawn up. Such a scheme should take into account the length of the network and the calculated air exchange in all rooms. According to the scheme of air ducts, parameters of air ducts and air distributors are calculated.
- The formula for calculating the cross-sectional area (estimated) of the duct:
S = L x 2,778 / V, where
Sс – area (calculated) section, cm ?;
2,778 – proportionality factor (hours / seconds, meters / centimeters);
L is the flow rate of air passing through the duct, m? / H;
V – air velocity, m / s.
- The formula for calculating the cross-sectional area (actual):
for round section:
S =? x d? / 400
for rectangular section:
S = A x B / 100, where
S – sectional area, cm ?;
D – diameter of circular section, mm;
A, B – height and width of rectangular section, mm.
The next step is to calculate the resistance of the air distribution network. In the calculation it is necessary to take into account each element of the network. It is performed by specialists using a specific program or calculator for ventilation parameters.
Next, the power of the heating element (heater) is calculated.
- The formula for calculating the power of the heater (P, kW):
P =? T x L x Cy / 1000, where
?T is the temperature difference at the inlet and outlet of the heater,? C;
Su is the heat capacity of air (taken equal to 0.336 W · h / m? /? C);
L – air capacity, m ?.
By adhering to the calculations of the requirements of SNiP, you can minimize the costs of all elements of the ventilation unit and its operation. Modern ventilation intake systems are equipped with a remote automatic control, which allows you to adjust the air and select the optimum mode of operation. Automatic control regulates the air temperature in the room, the fan speed, and also controls the operation of the heater.
Helpful advice! When choosing a ventilation system, give preference to installations with a digital automation system. The display of the control panel of this control displays information on the operation of the entire ventilation system.
More modern systems of automatic control allow you to control the contamination of the filter, to operate on a timer, to control the air humidifier.
As soon as the installation work is completed, tests of the ventilation systems are performed. Testing is documented by the Act of the executed works.
The following measures are included in the individual equipment tests:
- control of compliance of the installed equipment with the requirements of SNiP;
- tests of installed units in idle mode for four hours of continuous operation. This stage includes testing the starting devices, the level of heating of the electric motors, the quality of the glands, the control of the assembly and installation.
Testing of ventilation systems is carried out when the object has not yet been put into operation. Since the air distributors are installed most recently, tests are carried out without them. If the system is working properly, then when they are connected, the work will be normal. The act reflects that the system tests were carried out without connecting air distributors. Test measurements carried out by an independent laboratory that has the appropriate accreditation.
Proper operation of ventilation systems requires the following activities:
- scheduled inspection and troubleshooting of the ventilation unit;
- timely replacement of broken exhaust grille mounts;
- filter replacement:
- cleaning of ventilation systems from blockages;
- disinfection of air ducts.
The necessary information on the types of ventilation systems, their operation and maintenance will help in choosing the best equipment for the necessary air exchange in the room.